There was a time with early Transitions and crappy PALs people were told to order in a pair only, to reduce prismatic issues. But that time is past....
Beside the Optimization, the Surmount and the "S" are not comparable designs. The Surmount is a barrel shape, with a the widest point of the lens at...
Great list, but I would add a new "Fountain Shape" to this arsenal, which requires a slightly longer corridor but decreases spacial distortion, great...